1. Maintain closed, quarantine protected conventional colony of circa 7 to 8000 inbred (genetically defined) mice which includes BALB/c sublines, BALB/c congenic strains and other relevant inbred strains. 2. Production breeding of selected inbred and congenic mice for inductiontransplantation experiments. 3. Development of congenic strains of mice carrying specific markers designated by Project Officer. This includes monitoring the introgressive backcrossing. This involves the use of isozyme and restriction. fragment polymorphism marker identification technology. 4. Maintain and breed according to defined protocols a colony of wild mice including near and distant relatives of M. musculus domesticus. 5. Carry out plasmacytoma induction experiments which includes i.p. injection of pristane, treatment with pharmacological agents (indomethacin, etc.) and various transforming retroviruses. 6. Transplant, freeze and recover viable plasmacytomas and related tumors. 7. Respond to and send out transplantable tumors, pedigreed breeding mice and DNA samples from mice in the colony to responsible investigators in the US and abroad. 8. Isolate high molecular weight DNA from mice and from surgically removed tissues.